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A '12 1924. u G. F. TAYLOR THERMOSTAT Ogiginal Filed Dec. 15. 1923 aw r/zw V Y K G TA INVENTUR- E 5 NW N m w% ova M Reissued Aug. 12, 1924.-

UNITED STATES Re. 15,890 PATENT OFFICE.

GEORGE E. TAYLOR, or WASHINGTON, DISTRICT or COLUMBIA, DEDICATED, BY MESNE ASSIGNMENTS, To THE CITIZENS or THE UNITED STATES or AMERICA.

THERMOSTA'I. Original No. 1,484,802, dated February 26,1924, Serial No. 680,478, filed December 13, 1923. Application for reissue filed June 2, 1924. Serial No. 717,447. (FILED UNDER THE A0! OF'MARGH 3, 1883, 22 STAT. L, 625-.)

To all whom it may concern:

Be it known that I, GEORGE F. TAYLOR, a citizen of the United States of America, and an employee of the United States Dertment of Agriculture, residingi'n Washlngton, District of Columbia, have'invented a new and useful Thermostat.

This application is made under the act of March 3, 1883, chapter 143 (22 Stat.

625) and the invention herein described and claimed maybe used by the Government of the United States or any of its ofiicers or employees in the prosecution of work for the Government, or by any citizen of the United States, without payment to me of an royalty thereon.

The object of my invention is to provide a device by the application of which either automatic temperature control or automatic tem rature recording may be secured.

e invention will be fully described in connection with the accompanying drawing in which Fig. 1 shows a front elevation of the entire apparatus; Fig. 2 is a vertical sectional view thereof; Fig. 3 is an enlarged entary vertical sectional view illustratmg the key way of the grooved pin engaged by the keys, carried by the knurled nut housi Fig. 4 is a perspective view of the groov pin, and Fig. 5 is an enlar ed entary vertical sectional view il ustratlng the method of sealing the container ta is a tube with a bulb B at its upper end. To the lower end of the tube A is attached a rubber sack S. Just above this sack S a brass collar C fits securely around the lass tube A and screws into the expansion ulb D. P represents a spherical piston made of steel, bone or other substance which does not amalgamate with mercury. The stem E of the piston is attached to the sphere and extends through the bulb B.

When the apparatus is 1n use the expansion bulb D is filled with alcohol, ether, or,

other liquid of high coefiicient of expansion which does not injure rubber. The rubber sack S, the tube A and the lower part of the bulb B are filled with mercury. A rise of temperature in the liquid in the bulb D is accompanied by an increase in volume, which forces the mercury out of the rubber sack S into the tube A. A small air space is left around the sphere P. The surface tension of the mercury being very high, will cause the mercury to force the piston P upward, rather than flow around it. A lowering of the temperature in the bulb D will produce the reverse effect due to the atmospheric pressure on the surface of the mercury in B. The movement of the piston stem E may be employed to operate either a thermostat, a .thermo-regulator, or a. thermograph. 1

The accompanying drawing shows a thermostat, and illustrates the way in which it is operated by the device just described.

G is a frame which supports the entire apparatus, W andW are pivots on which the bulb D with its attached parts may be turned for greater convenience infilling or cleaning. The lock screws X hold the bulb and parts in their normal position. Q is a threaded and grooved pin which is raised or lowered by turning the nut M. On the lower end of the pin Q, two springs K are attached opposite each other. They are electrically insulated from each other and from the frames G. Each spring is connected by a wire 0 to a binding post N, the latter attached to-the frame but insulated from it. Between the springs are two contact points I. A small roller R made of an insulating material is attached to the end of each spring K. The plunger E is wedge shaped at its upper end and fits between the shallow grooves in the rollers R. \Vhen the plunger E movesupward due to a rise of temperature in the bulb D (described above), the rollers R are forced 1* combined with those of the more expansive It will be noted that no fouling liquids. of the mercury can take place in the working parts. The only place where oxidation can occur is on the surface of the mercury in the bulb B, Where it is of no consequence. It will be noted that the mercury is used only as a medium to transmit motion and that no electrical contact is made with it; also that shaking .or jarring has no significant efiect upon the operation of the instrument.

The electrical contacts in this thermostat are as heavy as those of an ordinary relay. It may therefore be used directly on an ordinary alternating current lighting circuit without the use of a relay.

I claim:

A thermostat consisting of a frame, a tube and an expansion bulb supported by said frame, said tube having an enlargement at its upper end and a rubber sack at its lower end, a spherical piston fittin loosely into said tube, a stem attached to sand piston at its lower end and extending upwardly through said tube, said expansion bulb adapted to enclose said sack, said sack, tube and thelower part of the said enlargement of said tube containing mercury, a small air space provided in said tube around said piston, said sack and lower end of said tube being hermetically sealed into said expansion bulb, said expansion bulb containing liquid, said piston and stem adapted to be moved in an upward or downward direction by means of motion imparted thereto by the rising or falling of the mercury in said tube resulting from compression or the release of compremion on the mercury in said rubber sack due to the expansion or contraction of the liquid in said expansion bulb.

GEORGE F. TAYLOR. 

